Method for Binarizing a Digital Gray Value Image to Generate a Binarized Gray Value Image and Arrangement for Carrying Out Said Method

1. A method for binarizing a digital gray value image to generate a binarized gray value image, the method comprising the steps of: generating a binary edge image from said gray value image so as to cause existing edges to be determined as line areas around an edge; after generating the binary edge image, making an inquiry as to whether the binary edge image shall become subjected to a smoothing process; in a first case, in which the binarized edge image shall not become subjected to a smoothing process, generating a first mean value of gray values of said gray value image in all regions which correspond to said line areas around an edge of the binary edge image with said mean value defining a threshold value for the generation of the binarized gray value image; in a second case, in which the binary edge image shall be subjected to a smoothing process, generating a smoothed binary edge image and generating an additional binary edge image based on the smoothed binary edge image, and generating a second mean value of gray values of said gray value image in all regions which correspond to line areas around an edge of the additional binary edge image with said second mean value defining a threshold value for the generation of the binarized gray value image; and, generating the binarized gray value image based on the first mean value in cases in which the binarized edge image has not become subjected to a smoothing process and on the basis of the second mean value in cases in which the binarized edge image has become subjected to a smoothing process.

2. The method of claim 1 , wherein said binary edge image is generated utilizing a gradient image generated on the basis of said gray value image.

3. The method of claim 2 , wherein said gradient image is generated by coupling a first directional gradient image with a second directional gradient image; and said first directional gradient image is formed in that gradients in said gray value image are determined in a first direction and said second directional gradient image is formed in that gradients in said gray value image are determined in a direction perpendicular to said first direction.

4. The method of claim 2 , wherein a first additional threshold value is assigned to said gradient image; and, gradient image point having a brightness magnitude above said first additional threshold value are set to logic 1 and gradient image points having a brightness magnitude less than said first additional threshold value are set to logic 0 so that said binary edge image is formed wherein the gradient image points set to logic 1 form line areas around edges and the gradient image points set to logic 0 form a background.

5. The method of claim 4 , wherein said first additional threshold value is one-quarter of the maximum gradient in said gradient image.

6. The method of claim 5 , wherein said binary edge image is subjected to a smoothing process utilizing a median filter.

7. The method of claim 5 , wherein a second additional threshold value is set; and, said second additional threshold value is half of the maximum gradient in said edge image which had been subjected to a smoothing process.

8. The method of claim 2 , wherein said gradient image is generated utilizing a difference operator selected from the group comprising: Sobel operator, Prewitt operator, Laplace operator, Kirsch operator and Roberts operator.

9. The method of claim 2 , comprising the further step of subjecting said gray value image to a smoothing process before generating said gradient image.

10. The method of claim 9 , wherein said smoothing process is performed with a median filter.

11. An image recording arrangement comprising a computer system including a digital computer and a computer program loadable into a memory of said digital computer, said computer program having a software code for carrying out a method for binarizing a digital gray value image to generate a binarized gray value image, the method including the steps of: generating a binary edge image from said gray value image so as to cause existing edges to be determined as line areas around an edge; after generating the binary edge image, making an inquiry as to whether the binary edge image shall become subjected to a smoothing process; in a first case, in which the binarized edge image shall not become subjected to a smoothing process, generating a first mean value of gray values of said gray value image in all regions which correspond to said line areas around an edge of the binary edge image with said mean value defining a threshold value for the generation of the binarized gray value image; in a second case, in which the binary edge image shall be subjected to a smoothing process, generating a smoothed binary edge image and generating an additional binary edge image based on the smoothed binary edge image, and generating a second mean value of gray values of said gray value image in all regions which correspond to line areas around an edge of the additional binary edge image with said second mean value defining a threshold value for the generation of the binarized gray value image; and, generating the binarized gray value image based on the first mean value in cases in which the binarized edge image has not become subjected to a smoothing process and on the basis of the second mean value in cases in which the binarized edge image has become subjected to a smoothing process.

12. A computer program stored on a non-transitory machine-readable medium, said computer program comprising a software code for carrying out a method for binarizing a digital gray value image to generate a binarized gray value image, the method including the following steps when executing the program on a computer: generating a binary edge image from said gray value image so as to cause existing edges to be determined as line areas around an edge; after generating the binary edge image, making an inquiry as to whether the binary edge image shall become subjected to a smoothing process; in a first case, in which the binarized edge image shall not become subjected to a smoothing process, generating a first mean value of gray values of said gray value image in all regions which correspond to said line areas around an edge of the binary edge image with said mean value defining a threshold value for the generation of the binarized gray value image; in a second case, in which the binary edge image shall be subjected to a smoothing process, generating a smoothed binary edge image and generating an additional binary edge image based on the smoothed binary edge image, and generating a second mean value of gray values of said gray value image in all regions which correspond to line areas around an edge of the additional binary edge image with said second mean value defining a threshold value, for the generation of the binarized gray value image; and, generating the binarized gray value image based on the first mean value in cases in which the binarized edge image has not become subjected to a smoothing process and on the basis of the second mean value in cases in which the binarized edge image has become subjected to a smoothing process.

13. The computer program of claim 12 , wherein said software code enables said digital computer to carry out said method when said program is loaded into said non-transitory machine-readable medium.